Sensitivity Enhancement of Ag-Ni Functional Bimetallic SPR Sensor Using Black Phosphorus in the Visible Region

Abstract In this seminal, a highly sensitive bimetallic layer for surface plasmon resonance (SPR) sensor applications is proposed with the BK7 prism, silver–nickel (Ag–Ni) bimetallic films, and hybrid structure of black phosphorus layer under angular interrogation technique. Sensitivity, minimum reflectivity (Rmin), DA, and FoM are the criterion for the sensing applications. By tuning these parameters, the maximum sensitivity of 347°/RIU is obtained with two-dimensional (2D) black phosphorus and the optimized thickness of the Silver layer at 633nm wavelength. 2D black phosphorus (BP) has attracted immense interest from the research community because of its unique properties like high charge density, direct bandgap, and better binding to the various molecules. The noble bimetallic layer-based SPR sensors have improved the sensor performance due to their exciting properties of large optical field enhancements follow on to the strong scattering and absorption of light. Herein, the Black Phosphorus-based SPR sensor is optimized with the thickness variation of the Silver layer due to ease of synthesis, a high degree of surface functionalization, and tunable Physico-chemical properties to the various sensing-medium refractive indices ranging from 1.330 to 1.335. Although there are many analogous sensors reported, limited attention has been paid to propose one, which exhibits the higher sensitivity, better DA, and superior FoM. The increased sensitivity of bimetallic layer and 2D, Black Phosphorus-based sensor providing promising applications in biosensing.